How to get your drain off cock or valve working if it is blocked or no water is coming out once you have loosened it off. We also cover how they work and cut one in half for you to look at!

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Welcome to today’s Plumberparts.co.uk video. Today, we’re gonna be looking at these little beasts. These are drain-offs. Now drain-offs are pretty simple things. They’re just valves, very similar to a tap that’d you’d have on a kitchen sink or something like that. And all they do is they drain out a part of a system or a set of pipework or radiators that you want to work on.
Now, they are so, so easy to use and they’re really, really easy to install as well. Firstly, you’ve got the valve jumper here. You’ve got the thread that threads the valve on to the seat that makes a seal. You’ve got this o-ring here that acts on the outside of this piece here to create a seal.
So what you can do, is you can thread one of these in, like so, get it so it’s turned off, and then put the outer thread like that in there as well. There are problems with these, you do get problems with them, and get stuck shut. If there was a tool I was gonna say you were gonna buy if you’re constantly gonna be working with one of these, it’s gonna be this: a square key. Because they are great for just getting in, they’ll go right on the end of that and they’re fine and you’d have to play around with a set of adjustables or a set of grips all the time which can end up mashing the square off on the end, buggering your grips up sometimes, and also, it’s just grief, because they’re often in awful positions, like down the side of boilers, next to a kitchen cupboard, or, I don’t know, a dog’s bed full of sick. Which has happened to me in the past.
So let’s have a look at how these work. We’re gonna cut one in half so you can get a good idea about how they’re actually done on the inside. Then, I’m also gonna show you how you’re gonna fix any problems about these when you open them up and they don’t let any water out. So, let’s go now. Right, so, we’ve cut our drain-off in half. Now firstly you’ll see that our seal sits right here on this seat here, and creates a seal just round there like so. Now the problems that can happen with these that means they don’t work is, sometimes this rubber seal can fall away and not work, or can get stuck in, sometimes you can take the whole of this piece here and be left with a jumper stuck in like that. You’ll know when that’s happened because you’ll be able to fit your finger in the hole and actually feel the end of the jumper like so. Your best bet there is to get ready. (laughs) Now, what you need to do is, we’ll look at this one here that we’ve got fully made-up. So what you’d have on the inside is something like this, it’s stuck in like so, and on the outside, you’ve taken everything out, like this, apart from, obviously, the jumper that we’ve got on here. What you do is you get a small amount of PTFE and just wrap that ’round this thread on its own. Remember, this bit’s stuck in here, still. Small amount of PTFE and wrap that ’round there on its own. Get your hose, and pop that on this outlet here ready. Then what you do is, you get a screwdriver, wiggle it in there and cock it, make sure you’ve got towels all over the place when you do this. But there’s only one way around it and this is the way. Cock this, and basically you’ll disturb that, and water will start to seep through. Often it’ll seep through beautifully out into your face and everywhere else. So make sure that the water’s cool that’s about to come out. Then, what you do, is you instantly, as soon as water starts coming out, you’ve got this bit sealed up already, you wind that in there, pop, seal that up. And then you can drain off as normal. When you’re finished, when that’s fully drained off, what you do is you take out this jumper, you can actually get these out when that’s happened. Then what you do, you’ve got new washers for these, you pop a new washer on the jumper when you’ve removed it, pop a little bit of grease on here, and push it all back together, and then screw it all back up how it was. And then you shouldn’t have any more problems and you’ll have a nice, fully-functioning drain-off. It never hurts, periodically, to just go around the house and just cut the drain-offs open and make sure water’s coming out. And never, ever over-tighten them. So, to recap, you’ve got the jumper on the outside, that we can do up and undo, then you have the actual twist mechanism on the inside here like so. Then you have a valve jumper with rubber washer over it. Look how beautifully that fits back together.